Cellulose fibers derived from wood pulp are used in a variety of absorbent articles, for example, diapers and feminine hygiene products. It is desirable for the absorbent articles to have a high absorbent capacity for liquid, as well as to have good strength characteristics for durability. Cellulose fibers for pad formation have traditionally been shipped to end users, that is, manufacturers of absorbent articles, in large densified rolls, or less frequently in compressed bale form. The end user fluffs the cellulose fibers, combines them with additives, such as absorbency enhancing polymers or specially engineered fibers, forms them into a pad, and then forms them into an absorbent article for the consumer. While this methodology is effective, it is desirable for some applications to provide absorbent webs that include additives to the manufacturer of the absorbent article in a form that can be incorporated directly into the absorbent article without the intermediate steps of fluffing, additive incorporation, and pad construction.
It is desirable to density webs before forming them into a roll to decrease the shipping costs. However, densified webs have insufficient strength for incorporation directly into absorbent structures. Therefore, the strength of the web must be increased, for example, by bonding the fibers together. The prior art suggests the simultaneous heating and compressing of a cellulose fiber web that has been combined with a thermoplastic bonding material to form a densified web with increased integrity. While this densifying technique provides higher bulk density and strength compared to densified webs of conventional non-bonded pulp, it has been found that the resulting densified web has a lower capacity for absorbing liquid than the non-densified, or fluffed, material normally incorporated into absorbent structures.
It is therefore desirable to provide a densified web of cellulose fibers that has an absorbent capacity superior to prior densified webs, and that has a wet integrity or strength that is substantially higher than non-bonded, densified webs.